The present invention relates to floor gratings, such as are commonly installed at building entrances and the like to provide means for removal of dirt, water and other foreign materials from the footwear of persons transiting the grating. Entrance gratings, as distinguished from entrance mats, typically are of rigid construction, and those of modern design frequently are assembled of a series of spaced-apart tread rails, secured together in side-by-side relation to form a rigid structure. Such grating structures typically are placed in a shallow recess, formed in the entrance flooring or walkway, so that the surface of the grating is flush with the surrounding floor.
A variety of structures are known and commercially available for use as rigid entrance grating. Representative of some of these are structures disclosed in the following prior U.S. Pat. Nos.: Berndt, Jr. No. 4,903,444, Carlton No. 4,727,704, Reifsnyder No. 4,112,640, Nagin No. 3,469,359, and Viehmann et al 3,383,822. Each of these discloses a grating structure comprised of a plurality of tread rails or the like arranged in a parallel, side-by-side relation and secured by a plurality of connecting elements extending at right angles to the tread rails and typically passing through openings in the tread rails. In many cases, the tread rails are arranged in closely spaced relation, so that a series of side-by-side tread rails forms an effectively substantially continuous surface for the support of common footwear, including high heeled shoes. At the same time, openings are available for the passage of debris, which is collected in the recess, below the top surface of the grating. Quite typically, these structures are formed of a light weight, extrudable metal, such as aluminum.
Although known designs of floor gratings are functionally adequate for many purposes, many of them tend to be unpleasantly noisy. Thus, in a typical case, aluminum tread rails are joined together by aluminum connecting elements, and the entire assembly is placed within a recess in a hard flooring, such as concrete, terrazzo or the like. When this structure is stepped on, disconcerting noise and clatter may be produced by the metallic elements moving relative to the hard flooring and/or relative to other, contacting metallic elements. This noise can be damped by the use of resilient pads, as in the case of the Berndt, Jr. U.S. Pat. No. 4,903,444. However, the sound-creating and sound-transmitting character of the metallic structure remains.
In accordance with the present invention, a novel and improved metallic floor grating, or rigid construction, is assembled in a manner that spacing of the tread rails is effected by special resilient spacing and support elements. These elements serve in a novel way to not only maintain the individual tread rails in a desired, closely spaced-apart relation, but also to support the tread rails slightly above the floor of the recess in which the grate structure in installed.
In a preferred embodiment, a plurality of metallic tread rails are joined together by means of connecting elements, typically tie rods, extending at right angles thereto. Between each adjacent pair of tread rails and associated with each connecting element is a resilient spacing and support element. In the complete assembly, the spacing and support elements are maintained under compression by the connecting elements, for form a rigid grate structure. To advantage, each of the spacing and support elements is formed with an opening or recess, arranged to receive the connecting element with which it is associated.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.